Reading comprehension failure has significant public health consequences. According to the National Assessment of Educational Progress (NAEP), approximately one-third of adolescents demonstrate deficient levels of reading comprehension, putting this group at great risk for poor academic and employment outcomes. While past NIH research has heavily focused on beginning reading and on word recognition skills, there has been increasing attention in recent years on adolescent reading failure and the processes involved in higher level comprehension. While deficits in lower level basic skills (word recognition/decoding) certainly contribute to our nation's difficulty with reading comprehension, research has shown that this does not fully explain reading comprehension failure in adolescents. Within this context, the goal of this project is to build upon previous behavioral and neurobiological findings including evidence suggesting that different types of reading comprehension deficits can be described by variability in three neuropsychological constructs: basic word recognition skills, broader oral language skills, and executive function (EF). We hypothesize that word recognition, language skill and EF are associated with brain circuits that should be identifiable using functional MRI and DTI, and that each skill contributes differently to different subtypes of impaired reading comprehension. There is also evidence to indicate that, even among standardized/typically used measures of reading comprehension, there is variability in the degree to which different tests demand the use of word recognition, language skill and EF. Based on this information, the current project proposes to build on this biologically- driven neuropsychological model of reading comprehension by drawing upon more theoretically-driven cognitive models of reading comprehension that have historically examined not only the learner's profile but also the complexity of the comprehension task and the text-specific cognitive demands. Therefore, the focus of this project is to understand the fundamental characteristics of the learner (including brain circuitry and cognitive profile) in relation to the complexity of the text that allows for skilled reading comprehension, or, conversely, impedes reading comprehension. Establishing these associations will allow for a rich understanding of brain-behavior connections in reading comprehension, and, more importantly, the combinations of learner profiles and types of tasks/texts that lead to reading comprehension success or failure. The plan is to establish the most parsimonious explanatory model of reading comprehension failure by pinpointing the neurobiological bases for it; this should allow for a clear understanding of subtypes of poor comprehension. Ultimately, these issues have significant implications for diagnosis/determination of reading difficulty, design of optimal remediation programs, and design of state outcome measures.